Spring-driven screw driver



June 28, 1949. A. GUNNING SPRING' DRIVEN SCREW DRIVER 2 Sheets-Sheet 1 Filed March 2, 1946 Inventor Aff'ed Gunnnj A MW HM@ June 28, 1949. A. GUNNING SPRING DRIVEN SCREW DRIVER 2 Sheets-Sheet 2 `Filed March 2, 1946 Agreed Gunning Patented June 28, 1949 UNITED STATES PATENT OFFICE 2,474,626 SPRING-DRIVEN SCREW DRIVER Alfred Gunning, Houston, Tex.

Application March 2, 1946, Serial No. 651,535

1 Claim.

This invention relates to a screw driver Iand more particularly to an automatic screw driver.

The primary object of the invention is to facilitate the entering of a screw into a screw hole in an inaccessible position.

Another object is automatically to start the screw into the screw hole so that it may subsequently be driven home.

The above and other objects may be attained by employing this invention which embodies among its features a shaft mounted to rotate about its longitudinal axis, a screw driving bit at one end of the shaft, means to rotate the shaft in a direction to drive a screw into a screw hole and releasable means normally holding said shaft against rotation.

Other features include a clutch for holding a screw in driving relation with the bit.

In the drawings, i

Figure 1 is a side view in elevation of a screw driver embodying the features of this invention,

Figure 2 is a longitudinal sectional view taken substantially along the line 2-2 of Figure 1,

Figure 3 is a transverse sectional view on an enlarged scale taken substantially along the line 3--3 of Figure 2.

Figure 4 is a transverse sectional view on an enlarged scale taken substantially along the line 4--4 of Figure 2,

Figure 5 is a perspective view of the screw driving shaft,

Figure 6 is a perspective view of one of the braking elements,

Figure 7 is a perspective view of one of the brake releasing elements,

Figure 8 is a transverse sectional view taken substantially along the line 8-8 of Figure 7, and

Figure 9 is a transverse sectional view taken substantially on the line 9-9 of Figure 2.

Referring to the drawings in detail my irnproved screw driver comprises a hollow cylindrical case I0 closed at one end by an axially apertured end wall I and provided at its opposite end with external screw threads I2 on which a cap I3 is adapted to be threaded. Formed in the case It! near its threaded end are diametrically opposed longitudinal slots I4 and arranged intermediate the ends of the case I0 is an axially apertured supporting wall I5. The cap I3 is provided with an axial aperture I6 which aligns with the apertures in the end wall and a partition wall I5, and formed in the threaded end I2 of the case III is an inwardly extending longitudinal rib I'I the purpose of which will be more fully hereinafter explained.

Mounted for rotation in the aligned, apertures in the walls II and I5 is a drive shaft I8 carrying intermediate its ends a stop flange I9 which rides against the inner face of the wall I5 and carried by the shaft is a squared portion 261 which is adapted to receive a key (not shown) which is rotatable in the opening I6 of the cap I3 for winding said shaft as will be more fully hereinafter explained. Carried by the shaft in spaced relation to the squared portion 20 is a clutch member 2| the purpose of which will be more fully hereinafter explained. Carried adjacent the end of the shaft I3 opposite the squared end 2U is an externally screw-threaded cylindrical `member 22 carrying at its cuter end a screw engaging bit 23, and threaded on the cylindrical member 22 is a screw retaining clip 24 which is adapted to hold a screw S in bit engaging position. That portion of the shaft I6 which extends beyond the case I0 is preferably tapered to lend flexibility, or if so desired a flexible extension may be connected to the end of the shaft which protrudes beyond the end wall I I.

Fixed to the shaft I6 adjacent the stop collar I9 is one end of a volute spring 25, the opposite end of which is fixed to the case Il) so that when the shaft is rotated by fitting a key on the squared end 2U and turning it, the spring 25 will be placed under tension and will tend to rotate the shaft in the opposite direction. It is to be understood of course that the spring 25 is to be fixed to the shaft in such a manner that in unwinding the screw S will be turned in the proper direction to enter the screw hole into which it is to be fitted.

Riveted or otherwise attached as at 26 to the case III adjacent the forward end of each slot I4 is a bowed arm 21 to the rear end of whichl is pivoted as at 28 a bowed arm 29 carrying at its free end a shoe 30 which bears against a flange 3| carried at the rear end of a clutch member 32 which is adapted to cooperate with the clutch member 2| in holding the shaft I8 against rotation under the influence of the spring 25. The flange 3| is provided with a notch 33 for the reception of the rib I1 by means of which the clutch member 32 is held against rotation, and bearing against the clutch member 32, and the inner face of the rear `wall of the cap I3 is a compression. coil spring 34 which urges the clutch member 32 into frictional contact with the clutch member 2|. The clutch member 32 is formed with an axial opening 35 for the reception of the shaft I8 and its exterior is shaped to conform to the s. interior of the cup-shaped member 2l as will be readily seen upon reference to Figure 2.

In operation it will be understood that a screw S is placed in position on the end of the shaft I8 with the bit 23 entering the screw slot and the clip 24 is then threaded onto the cylindrical member 22. Having placed the screw in position on the screw driver bit a key having a square socket is fitted on the squared end 20 of the shaft I8 and the shaft rotated to load the spring 25, it being understood that the grips formed by the members 21 and 29 are squeezed during the turning oper-a tion to disengage the clutch members 2l and 32.

Having loaded the spring 25 pressure is released on the grips, thus allowing the clutch member 32 to enter the clut-ch member 2| and frictionally hold the shaft against rotation. The screw `'S is then guided to the screw hole which it is to enter and upon applying pressure to the grips it will be obvious that the clutch member 32 will be disengaged from the clutch member 2l thus permitting the shaft I3 to rotate and drive the Screw S into the screw hole, Obviously the pressure may be applied to the grips for a period of time sufficient to drive the screw S home, or may be only sufficient to permit the screw to enter the screw hole after which the screw may be turned or tightened by manual rotation of the screw driver. It will be evident upon releasing pressure on the grips the clutch member 32 will again enter the lcuplshaped clutch member 2| and arrest rotation of the shaft l 8.

While in the foregoing there has been shot/n and described the preferred embodiment of this 'invention rit is to be understood that Y minor changes in the details of construction, combination and arrangement of parts may be resorted to Without departing from the spirit and scope ofthe invention as claimed.

I claim:

In a spring driven screw driver, an elongated hollow handle having a pair of opposed elongated longitudinal slots opening therethrough, a shaft extending longitudinally through the handle, said shaft being mounted to rotate about its longitudinal axis and being held against longitudinal movement relative to the handle, a screw driver bit carrie-d by the shaft, a drive spring within the handle, said drive spring being connected to the shaft .and to the handle for imparting rotary motion to they shaft, a rotary Yclutch collar iixed to the shaft within the handle, a slidable clutch collar surrounding and rotatable with respect to the shaft adjacent the rotary clutch collar, means carried by thel handle to hold the slidable clutch collar against rotation relative to the handle, a clutch spring Within the handle, said clutch spring ibearing ithe handle and on the slidable clutch collar to urge said slidable clutch collar to move Vlongitudinally of the shaft and into frictional engagement with the rotary collar, a pair of opposed toggle action hand grips carried by the handle, said hand grips bowing `outwardly through the opposed slots, and shoes carried by the hand grips and bearing on the slidable clutch collar in opposed relation to the clutch spring Awhereby pressure on the hand grips will move the slidable clutch collar against the effort of the clutch spring and out :of engagement with the rotary clutch collar.

` .ALFRED GUNNIN G.

REFERENCES ACIT-E1) The following referenlces are of record in the file of thisv patent:

UNITED STATES PAT'ENTS 

